Transmitter



.Sept. 1, 1925. 1,551,723

F. H. N. WOHLERS TRANSMITTER Filed April 14. 1921 IIIIIIIIIII ATTORNEYJ.

Patented Sept. 1, 1925.

UNITED STATES 1,551,723 PATENT OFFICE.

FRIEDRICH H. N. WOHLERS, OF JAMAICA, NEW YORK, ASSIGNOR TO DICTOGRAPHPRODUCTS CORPORATION, A CORPORATION OF VIRGINIA.

TRANSMITTER.

Application filed April 14, 1921. Serial 110. 461,283.

To all whom it may concern:

Be it known that I, FRIEDRICH H. N. WOHLERS, a citizen of the UnitedStates, residing at Jamaica, in the county of Queens and State of NewYork, have invented certain new and useful Improvements in Transmitters,of which the following is a full, clear, and exact description.

In carbon ball transmitters utilizing a plurality of ets of a conductingelement and engaged by a diaphragm, such as disclosed for example in U.S. Patent No. 844,635, it has been found that if the transmitter issubjected to jars or shocks such as are occasioned by dropping of thetransmitter, the diaphragm often springs or flexes away from theconducting element or pockets sufliciently to allow the small balls toescape entirely from the pockets of the elements or to become wedgedbetween the diaphragm and the 01'- tion of the conducting elementsurroun ing the pockets, with the result that the diaphragm eithercannot vibrate at all or the absence of the balls from the pocketsprevents or limits the passage of current between the diaphragm and theconducting element.

The object of my invention is to provide a carbon ball transmitter inwhich it is impossible for the balls to get out of place or lost, togenerally improve and sim lify the construction of transmitters of t istype,

eleminate difficult and expensive machine work in their manufacture, andimprove the attachment of the face cap to. the casing. Other objects andadvantages will be ap parent from the following description and thenovel features of my invention will be particularly pointed out inclaims.

In carrying my invention into practice I support an abutment adjacentthe face of the diaphragm and opposite the conducting element, butspaced therefrom sufiiciently to permit of the normal vibration of thediaphragm and acting to limit excessive movement of he diaphragm such aswould release the b lls from the cavities of the conducting element. Thesame abutment is also preferably utilized as the support for the facecap of the instrument. The invention also com rises certain details andarrangements w ich will be hereinafter more particularly described inconnection with the illustrated embodiment of my invention.

very small carbon balls in pock- In the drawings:

Fig. 1 is a front elevation of a transmitter constructed in accordancewith my in- Vention;

Fig. 2 is a section of the same taken substantially along the line 2-2of Fig. 1;

Fig. 3 is a plan of a detail of the transmitter, and

Fig. 4 is a plan of the cup carrying the conductin elements.

A suita le handle 1 is provided at one end with connections 2 fora twincable 3 entering the same and by means of which the instrument isconnected to any suitable external circuit. The opposite end of thehandle terminates in a casing 4 having an open face in which is disposedthe trans mitter mechanism proper. A cup 5 is removably disposed withinthe bottom of the casing 4 and carries a pair of carbon blocks 6 whichare secured thereto by screws 7. Insulating pads 8 are interposedbetween the carbon blocks 6 and the bottom of the cup for insulating theblocks therefrom and suitable insulation 9 is interposed between the twoblocks. A contact plate 10 is interposed between each block and itsinsulating pad and has an enlarged aperture 11" for,the passage of thesecuring screw 7.

insulating sleeve 12 surrounds each screw 7 so as to insulate it fromthe contact plate .10 and carbon block, the head of the screw beincountersunk below the face of the carbon lock. Each block is providedwith a plurality of cavities or depressions 13 in its outer face, inwhich are disposed a plurality of small carbon balls 14. A diaphragm 15of conducting material is clamped across the up er face of the cup atthe periphery thereof by means of a suitable disk like element or member16 which is threaded into the interior of the open end of casing 4,suitable gaskets 17 being interposed between the diaphragm and both theelement 16 and the cup 5 so as to insulate the diaphragm from thecasing. The depth of the on 5 is such as to cause the diaphragm to beisposed in a slightly spaced relation to the outer faces of the carbonblocks and retain the balls 14 within the cavities and at the same timebe free to vibrate slightly without contacting with the carbon blocks.The disk-like element 16 has an o ening 18 in its central portion whichis bri ged by arms 19 carrying at their junction 9. boss 20. The

necessary for its normal vibration and prevent movement to an extentsufficient to release the balls from the cavities. The boss is providedwith a threaded aperture 21 which receives a threaded stem 22 of a capplate 23 which closes the outer face of the casing 4. The cap plate isprovided with mitter should be accidentally -ishes or suitable openings24 for permitting entrance of the sound waves to the casing in order toactuate the diaphragm and through it vary the resistance of the circuit.The carbon blocks are connected through their contact plates 10 andwires 11 with the connections 2 in the opposite end of the handle.

The external circuit is connected to the instrument by cable/3, thecurrent passing through one .of the wires 11 to one of the contactplates 10, the carbon block 6 carried thereby, the carbon balls in thepockets of that block, a diaphragm in contact therewith, through thediaphragm, then through the carbon balls of the other carbon block whichare in contact therewith, the other carbon block, its contact plate 10and the corresponding wire 11 back to the cable 3. As the sound wavesenter the apertures 24 of the casing they impinge upon the diaphragm andset the latter in vibration. The diaphragm in vibrating displaces the.carbon balls in their pockets and by this displacement varies theresistance through the same and causes a fluctuation in the. currentpassing through the circuit described. This variation in the current inthe circuit is utilized at another point in the circuit for thereproduction of the sound waves in a manner well known in the art. Ifthe transdropped or subfected to severe shocks, the diaphragm Wll beprevented from moving away from the carbon blocks sufliciently to allowthe balls to esca e from the pockets, owing to the contact 0 thediaphragm with the abutment 20 upon an excessive flexure of thediaphragm. The boss also acts as a support for the stem projecting fromthe cap which eliminates the necessity of threadmg the cap to fit thecasing and enables the cap to stamped from sheet metal and the stemwhich can be inexpensively produced in automatic I machines can beattached thereto by riveting.

The ca can be produced in various fineslgns to match furniture or otherfittings a d attached to a standard transmltter so as to eliminate thenecessityof producing the entire transmitter in various particularfinishes thus considerably lessenmeg-1 the cost and stock which shouldbe carn It will be obvious that various details and changes in theconstruction herein described and illustrated may be made by thoseskilled in the art within the principle and scope of the invention.

I claim: 7

1. In a telephone transmitter, a block of conducting material havingcavities in a face thereof, a diaphragm 1n juxtaposition to but slightlyspaced from said block and cavities, a plurality of small balls confinedin each of said cavities by the diaphragm, and an abutment adjacent tobut slightly spaced from the face of the diaphragm opposite to the blockwhereby movement of the diaphragm away from the block sufficiently torelease the balls from the cavities will be prevented withoutrestricting normal vibratory movement of the diaphragm.

2. In a telephone transmitter, a conducting element having a cavity in aface thereof, a diaphragm supported in juxtaposition to but slightlyspaced from the said face of the element, a plurality of small ballsconfined within the cavity by the diaphragm, and means permitting normalvibratory movement of the diaphragm but preventing an amplitude ofmovement of the same sufficient to release the balls from the cavity.

3.111 a telephone transmitter, a casing, a conducting element having a.cavity in a face thereof carried within the casing, a diaphragmsupported in juxtaposition to but slightly spaced from the said face ofthe element, a plurality of small balls confined within the cavity bythe diaphragm, and a membercarried by the casing for clamping thediaphragm and element in osition in the casing and having a portion 1njuxtaposition to but slightly spaced from the central portion of thediaphragm opposite the conducting element for preventing an amplitude ofmovement of the diaphragm sufficient to release the balls from thecavity.

4. In a telephone transmitter, a. casing, a conducting elementv having acavity in a face thereof carried within the casing, a dia phragmsupported in juxtaposition to but slightly spaced from the said face ofthe element, a plurality of small balls confined Within the cavity bythe diaphragm, a member carried by the casing for clamping the diaphragmand element in osition in the casin and having a portion in juxtapdsition to ut slightly spaced from the central portion of the diaphragmopposite the conducting element for preventing an amplitude of movementof the diaphragm suf-- ficient to release the balls from the cavity, anda perforated cap for closing the casing carried by the member.

5. In a telephone transmitter, a casing, a conducting element having acavity in a face thereof carried withln the casing, 11.

diaphragm supported in juxtaposition and member having aperturespermitting passage of sound waves to the diaphragm from the exterior ofthe casing.

6. In a telephone transmitter, a casing having an open face, a cupremovably disposed in the bottom of the casing and'open: ing toward theopen face of the casing, a

' conducting element carried within the cup.

and-having a cavity in its outer face, a diaphragm closing the-open faceof the cup and passing in uxtaposition to but spaced slightly from thesaid outer face of the conducting element, a plurality of small ballsconfined within the cavity by the diaphragm,

and a member adjustably engaging with the casing to' clamp the diaphragmagainst the edge of the cup and both againstvthe rear wall of thecasing.

7. In a telephone transmitter, a casing having an open face, a-cupremovablydis posed in the bottom of the casing and opening toward theopen face of the casing, -.a conducting element carried within the cupand. having a cavity in its outer face, a diaphragm closing the openface of the cup and passing injux-taposition to but spaced slightly fromthe said outer face of the conducting element, a plurality of smallballs x confined within the cavity by the diaphragm, and a memberadjustably engaging with the casing to clamp the diaphragm .balls fromthe cavity.

against the edge of the cup and both against vthe rear wall, of thecasing, said member having an opening for the passage of sound wavestothe diaphragm and also having a portion in juxtaposition to butslightly s aced from the central portion of the diap ragm for preventingmovement of the diaphragm away from the conducting. element to an extentsuflicient (to release the 8. In a telephone transmitte a casing havingan open face,. a cup removably disosed in the bottom of the casing andopenmg toward the open face of the casing, a conducting element carriedwithin the cup and having a cavity in its outerface, a diaphragm closingthe open face of the cup and passing in juxtaposition to but spacedslightly from the said outer face of the conducting element, a pluralityof small balls confined within the cavity by the diaphragm, and a memberadjustably engaging with the casing to clamp the diaphragm against theedge of the cup and both a 'ainst the rear -wall of the casing, and aper orated cap detachably carried by the member for closing the casing.r

9. In a telephone transmitter, a casing having an open'face, a onremovably disposed in the bottom of the casing and open: ing toward theopen face of the casing, a conducting element carried within the cup andhaving a cavity in its outer face, a dia hragm closing the open face ofthe cup an passing in juxtaposition to but spaced slightly from the saidouter face of the conducting element, a plurality of small balls withthe casing to clamp the diaphragm against the edge of the cup and bothagainst the rear wall of the casing, said ,member having an opening forthe passage of sound waves to the diaphragmand also having a portion injuxtaposition to but slightly s aced from-the central portion of thediap ragm for preventing movement of the diaphragm away from theconducting ele-' ment to an extent suflicientto release the,

balls from the cavity, and a perforated cap detachably carried by themember for closing the open face of the casin 10. In a telephonetransmitter, a casing having anopen face,'a cup removably disposed inthe bottom of the casing and openmg toward the open face of the casing,a conducting element carriedw-ithin the cup and having a cavity in itsouter face, a diaphragm closing the open face of the cup and passing injuxtaposition to but, s aced slightly from the said outer face '0 theconducting element, a plurality of small balls confined within thecavitv hv the diaphragm, a member-adjustably engaging with thecasing toclamp the diaphragm against the edge of the cup and both against therear Wall of the casing, said member carryconfined within the cavity bythe dia 'phragm, a member adjustably engaging ing a boss at its centralportion. in juxtaposition to but slightly-spaced from the centralportion of the diaphragm for preventing movement of the diaphragm awayfrom the conducting element to an extent sufficient to release the ballsfrom,the-cavity, a cap for closing the casing and havingaa threaded stemprojectingcentrally therefrom, said boss having athreadedapertureforflreceivingsaidthreaded stem thereby and detachablysecuring the cap to the casing, said cap and member havingopen portionspermitting the passage of sound waves-from the exterior of the casingtothe diaphragm.

In witness whereof I hereunto subscribe" my. signature.

FRIEDRIOH'I-I. N; .Wo'HmaRs.

fies

